Physics Nobel Laureates (2021) Predict the Extent of Global Warming

Three scientists shared this year’s Nobel Prize in Physics for the physical and mathematical models developed by them for explaining the underlying Order in the Disordered Systems present in nature, and predicting accurately the Climate Change due to Global Warming.

Syukuro Manabe (90), born in Japan) and Klaus Hasselmann (89), of Germany) were awarded the Nobel Prize (2021) for their work in developing mathematical models for forecasting Earth’s climate based on reliable predictions of Global Warming. The second half of the prestigious prize went to Italian scientist Giorgio Parisi (73) for studying the disorder in physical systems, ranging from those as small as the insides of atoms to the planet sized. He predicted how these diverse systems move in chaotic ways and there is an inherent order in their haphazard motion. This has applications in prediction of climate change and many other natural phenomena.

Manabe, now at Princeton University, created the first-ever climate models (in 1967) that forecast what would happen as carbon dioxide built up in the atmosphere. This gas traps heat, but his work showed how global warming will worsen and how fast will  this happen, depending on the extent of carbon dioxide pollution. He accurately predicted the warming that actually occurred in the last 50 years. The model also gives estimates of the warming of the Earth in future. 

Klaus Hasselmann, of the Max Planck Institute for Meteorology in Hamburg, showed how the climate and weather are connected and how the variable and random weather of the atmosphere gets converted into slowly changing signals in the oceans. These large–scale changes in the oceans then modulate the climate. He prepared climate models that are accurate, despite the changing nature of the weather. Hasselmann also pointed to the human influences on the climate and the increase in air temperature due to emissions of carbon dioxide (and some other gases in the atmosphere) and predicted disastrous consequences like rising seas, increased extreme rainfall and stronger hurricanes, and wildfires which were observed  decades later .

Giorgi Parisi, of Sapienza University of Rome, studied some of the most disordered physical systems in nature, and showed that actually even these behave in an orderly fashion. He established numerous equations that accurately represent an array of chaotic climate parameters. His models enable us to understand complex systems in many fields, such as Mathematics, Biology, Neuroscience, and Machine Learning (ML). For the first time, Parisi discovered hidden patterns that explain the way these systems work and gave the solutions to a vast number of such problems. The models are based upon detailed statistical calculations of such parameters as average values, standard deviations, highest and lowest measured values (among others), for a large number of continuousy varying complex systems.

Role of Water vapour and carbon dioxide in raising the atmospheric temperature is an important factor responsible for global warming. Manabe and Hasselmann found that when carbon dioxide in air doubles, global temperature increases by over 2°C. There  is much stronger warming in the Arctic, a decrease in ice and snow cover, melting of glaciers and icebergs, an increase in the average global rate of precipitation and a cooling (between – 510C and – 150C), of the stratosphere, the atmospheric layer where most aircraft reach their cruising altitude. They also predicted increased dryness over some continents, leading to widespread forest fires. The quantity of water vapour in air is dependent on temperature. More carbon dioxide makes the air warmer, so that more water vapour is held in the air. This increases makes air temperatures rise further. If the carbon dioxide level drops, water vapour condenses and the temperature falls.

Solar Radiation falling on the Earth’s surface is partly reflected and partly absorbed by the gases in the air, thereby heating the atmosphere. This (Greenhouse Effect) involves complicated radiative processes of  Infra Red (IR) or heat rays in air. Absorptions of heat takes place by Carbon dioxide, Water vapour, Methane, Oxides of Nitrogen, and gases used in Air-Condioning systems, called greenhouse gases (GHG). This continuous accumulation of heat is responsible for the excessive atmospheric heating. (Part of this heat, however, is essential to some extent for the Earth. If the atmosphere did not absorb a part of the incident solar radiation, Earth’s  surface temperature would barely exceed  –18°C.)

Predictive Models of Weather and Climate are mathematical formulations of interconnected complex meteorological phenomena. Weather forecasting reqires the hourly and daily recording of changes in the atmosphere in a limited area of interest. Earlier, weather forecasters used to extrapolate future weather from changes recorded over the previous days and their past experience. Now,  models are prepared as systems of equations that are based on the physical laws that govern the weather. The solution of these equations, using data from today’s weather, predicts tomorrow’s weather.

Climate is the average weather over the oceans and the land surfaces for several decades.  The factors that affect climate include many variables like motion of air, the flow of electromagnetic radiations (such as sunlight), motion and tilt of the Earth and the condensation of water vapour, across the Earth, with time.  These three scientists used much faster computers that enabled them to create models representing the entire global atmosphere. This involves an interconnected web of thousands of mathematical relations that simulate variables like jetstream and monsoons and then predict the future climatic changes.

One-D and 3-D Climate Models were developed by them to study the complex transport of air due to convection and the latent heat of water (heat required to vaporize water or heat released when vapour condenses to liquid form). The pressure dependent, 1-D studies predict a rise in temperatures closer to the ground while the upper atmosphere is colder. The 3-D models include horizontal, latitude-longitude dependent, changes in the air envelope surrounding  the planet.

Geographically, Earth’s weather changes as the solar radiation is not evenly distributed over time. Fewer solar rays reach the higher latitudes, but more rays fall on the Equator. The tilt in the Earth’s axis of rotation produces seasonal changes. The differences in density between warmer and colder air cause heat transfer between different latitudes and between oceans and land areas. The Greenhouse gases only incease these changes and make global warming much worse. The amounts of carbon dioxide and other GHG in the atmosphere need to be reduced, specially because the amount of water vapour present in the Earth’s atmosphere can not be controlled.                                                                                                                                        

New Discoveries of Manabe, Hasselman and Parisi link Climate, Weather, and the Complex Disorder in nature. This has enabled scientists to predict how the chaotic and coupled behavior of the Atmosphere, Oceans and Land surfaces will change in future. Our ability to understand these complicated systems has increased incredibly by their achievements.

Intergovernmental Panel on Climate Change (IPCC) of the U.N. and former U.S. Vice President Al Gore were given the 2007 Nobel Peace Prize for their concerns about climate change and work for averting the impending climatic crisis due to global warming. Some people had dismissed it as a political move. These three Nobel Laureates have asked the world leaders to plan for curbing global warming, at the high-level Glasgow meeting (from 31 October to 12 November 2021), with focus on short-time and long-time negotiations to reduce the greenhouse gases.

Professor Dr Surjit Singh Bhatti (surjitsinghbhatti@gmail.com) is a retired Professor & Head of Physics Department and Dean of the Faculty of Sciences, Guru Nanak Dev University, Amritsar, India).

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